Cannibalistic tadpoles and matricidal worms dispute evolution

A recent study identifies phenotypic plasticity as the ability of tadpoles to change how they look and act, and how their tissues function, in response to their environment. If the pond also contains fairy shrimp, some tadpoles turn into aggressive carnivores and sometimes, the carnivorous tadpole stage becomes entrenched – without the need for a dietary trigger. This plasticity has also been confirmed in lizards, roundworms, and yeast. When yeast is exposed to the herbicide paraquat, the yeast copes by eliminating some or all of the DNA in their mitochondria, the cells’ energy-producing organelles.

Some consider this a classic example of “plasticity-first evolution”. On the surface, the findings vindicate Lamarck. The plasticity those changeable tadpoles display is built into their genetic code. And when an “acquired” trait does become “permanent”, it is because of mutations that “fixed” the plastic trait – a process biologists call genetic assimilation.

Since plasticity is a built-in trait of so many organisms, it has obviously been mistaken for “evolution”. “Permanent” claim is meaningless given all organisms populations are ever-changing. The main questions are “what are the limits of plasticity?” and “what happens over the very long time?” The evidence to date is very clear:

Plasticity is a built-in widespread if not universal characteristic of organisms

It is limited in scope to a few traits like color, behavior, and metabolism

Plasticity is reversible rather than cumulative

It is not divergent as toads, lizards, roundworms, yeast, etc. never turn into not-toads, not-lizards, and so on.

This is a repackaging of the same stories sold as proof of “evolution”. Darwin’s finches, the peppered moth, antibiotic resistant bacteria and, why not, the tanning humans. Too bad all these not only do not diverge into new organisms, but they all have been shown to revert eventually when the stimulus is removed. Finches change back their beaks depending on environment and never turn into non-finches, the black moths reversed to white and never to not-moths, antibiotic resistance disappears from the population when we reduce the use of antibiotics (see NIH recommendation), and neither light-skinned Nordics, nor dark-skinned Mediterraneans turn into not-humans under any circumstance.